//
// Created by 李梦凡 on 2019/10/21.
//

#include "sprite_renderer.h"


SpriteRenderer::SpriteRenderer(const Shader &shader) {
    this->shader = shader;
    this->initRenderData();
}

SpriteRenderer::~SpriteRenderer() {
    glDeleteVertexArrays(1, &this->quadVAO);
}

void
SpriteRenderer::DrawSprite(const Texture2D &texture, glm::vec2 position, glm::vec2 size, GLfloat rotate,
                           glm::vec3 color) {
    // Prepare transformations
    this->shader.Use();
    glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
    model = glm::translate(model, glm::vec3(position,
                                            0.0f));  // First translate (transformations are: scale happens first, then rotation and then finall translation happens; reversed order)

    model = glm::translate(model,
                           glm::vec3(0.5f * size.x, 0.5f * size.y, 0.0f)); // Move origin of rotation to center of quad
    model = glm::rotate(model, rotate, glm::vec3(0.0f, 0.0f, 1.0f)); // Then rotate
    model = glm::translate(model, glm::vec3(-0.5f * size.x, -0.5f * size.y, 0.0f)); // Move origin back

    model = glm::scale(model, glm::vec3(size, 1.0f)); // Last scale

    this->shader.SetMatrix4f("model", model);

    // Render textured quad
    this->shader.SetVector3f("spriteColor", color);

    glActiveTexture(GL_TEXTURE0);
    texture.Bind();

    glBindVertexArray(this->quadVAO);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    glBindVertexArray(0);
}

void SpriteRenderer::initRenderData() {
    // Configure VAO/VBO
    GLuint VBO;
    GLfloat vertices[] = {
            // Pos      // Tex
            0.0f, 1.0f, 0.0f, 1.0f,
            1.0f, 0.0f, 1.0f, 0.0f,
            0.0f, 0.0f, 0.0f, 0.0f,

            0.0f, 1.0f, 0.0f, 1.0f,
            1.0f, 1.0f, 1.0f, 1.0f,
            1.0f, 0.0f, 1.0f, 0.0f
    };

    glGenVertexArrays(1, &this->quadVAO);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindVertexArray(this->quadVAO);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), (GLvoid *) 0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}
